Houston is a city of jarring juxtapositions, the type of place where one can find a quiet custom shirtmaker—in league with the most storied of Savile Row—lying low on a gaudy suburban strip a block beyond Kwik Kar Lube & Tune and across the street from a purveyor of erotic novelties. Its neighbors notwithstanding, Hamilton Custom Shirtmaker's clubby headquarters, a dark-paneled parlor and adjoining workshop (the goods are made in full view on site), continues a bespoke tradition dating back to 1883, when the family-owned company first opened its doors to an emerging Texas gentry of cattlemen and cotton traders. (Oil barons and Fortune 500 executives later joined the mix.)

"For years, our trade was mostly local, and pretty much word of mouth," explains David Hamilton, 28, who last year took over stewardship of the venerable brand with his sister, Kelly, 31. Together, the fourth generation of impeccably tailored Hamiltons are modernizing the business and deepening its niche in an increasingly global fashion industry. "We're part of a small but very international network," says Kelly, naming Charvet in Paris, Turnbull & Asser in London, and a few other peers in Los Angeles and Milan.

Beyond the front-room displays—shirts sport variations on elements like the yoke, including, naturally, Western—two vast walls of metal shelves stacked floor to ceiling with more than 500 bolts of fabric beckon customers to peruse. The full range of long-staple cotton weaves is here, from top Italian and Swiss mills such as Testa, along with heaps of color, texture, and pattern options.